P0734 2015 GMC Sierra Code - Transmission 4th Gear Ratio Incorrect
Quick Answer
The transmission turbine speed sensor and vehicle speed sensor are hall-effect sensors. Common causes include Low transmission fluid level, Shift solenoid mechanical fault, Faulty Turbine Sensor. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0734 2015 GMC Sierra indicates Transmission 4th Gear Ratio Incorrect.
- Common causes
- Common causes include Low transmission fluid level, Shift solenoid mechanical fault, Faulty Turbine Sensor.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P0734 2015 GMC Sierra Description
The TCM provides a 9 V reference circuit and a signal circuit to each of the sensors. As the 1-2-3-4-5-6 clutch piston housing and transmission output shaft or transfer case output rotates, the sensors produce a signal frequency based on the teeth on the reluctor wheel. The TCM calculates the transmission gear ratio based on the speed sensor signals and compares the calculated gear ratio to the commanded gear ratio.
The Diagnostic Trouble Code (DTC) will be set when the TCM detects the calculated gear ratio with 4th gear commanded differs from the known 6th gear ratio for 2 s.
What are the Possible Causes of the DTC P0734 2015 GMC Sierra?
- Low transmission fluid level
- Shift solenoid mechanical fault
- Faulty Turbine Sensor
- Faulty Output Speed Sensor
How to Fix the DTC P0734 2015 GMC Sierra?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0734 2015 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about P0734 2015 GMC Sierra Code
1. What does OBDII code P0734 mean on a 2015 GMC Sierra?
P0734 indicates that the transmission control module (TCM) has detected an incorrect gear ratio in 4th gear.
2. What are the common symptoms of code P0734 on a 2015 GMC Sierra?
Symptoms may include slipping in 4th gear, harsh shifting, decreased fuel efficiency, or the check engine light being illuminated.
3. What causes the P0734 code on a 2015 GMC Sierra?
Common causes include low transmission fluid, faulty shift solenoids, worn clutch packs, a damaged transmission valve body, or internal transmission issues.
4. Can driving with a P0734 code damage my 2015 GMC Sierra?
Yes, continuing to drive with this issue can cause further damage to the transmission and result in costly repairs.
5. How do I fix the P0734 code on a 2015 GMC Sierra?
Repairs may involve checking and topping off transmission fluid, replacing faulty shift solenoids, repairing internal transmission components, or reprogramming the TCM.
6. Is low transmission fluid a common cause of the P0734 code?
Yes, low or contaminated transmission fluid can lead to gear slippage and incorrect gear ratio detection.
7. How much does it cost to fix code P0734 on a 2015 GMC Sierra?
Costs can vary widely depending on the issue, ranging from $100 for fluid replacement to several thousand dollars for a full transmission rebuild.
8. Can a faulty transmission control module (TCM) trigger code P0734?
Yes, a malfunctioning TCM can send incorrect signals, leading to gear ratio problems and triggering the P0734 code.
9. How do I diagnose the P0734 code on my 2015 GMC Sierra?
Start by checking the transmission fluid level and condition, inspecting wiring and connections, and using a scan tool to monitor shift solenoid performance and gear ratio data.
10. Will clearing the P0734 code fix the issue on a 2015 GMC Sierra?
Clearing the code may turn off the check engine light temporarily, but it won’t resolve the underlying issue, and the code is likely to return.
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